Nano-scale resolution optical pickup for reading/writing ultra-high density data on CD and DVD data storage elements

ABSTRACT

A single high resolution holographic pickup, for reading/writing both a CD and DVD optical recording medium, has an electrical tuning control for applying a DC and AC signal to a tunable Bragg cell, which AC is phase locked with respect to the fundamental repetition frequency of the recorded data on the CD to produce accurate tracking. A special high resolution holographic lens is recorded within the Bragg cell that focuses the light signals read off of the optical storage mediums upon a pickup detector, and its focal length is varied to read a selected CD and or DVD from a group of CDs or DVDs in response to changes in the DC applied to the Bragg cell. The holographic lens within the Bragg cell is formed by an interference pattern produced by interfering light emitted from the tip of a one micron optical fiber and a plane broad light beam.

RELATED APPLICATIONS

[0001] This is a divisional of patent application Ser. No. 09/642,204filed Aug. 19, 2000, now U.S. Pat. No. ______. The application isincorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to the field of optical dataprocessing.

[0003] Homodyne and heterodyne detection is one of the most importantconcepts in information processing theory. Several other concepts areassociated with it, such as phase-sensitive detection, lock-indetection, frequency and time-division demultiplexing and base-banddemodulation, time-integrative correlation, and many other devices,which can be fined the literature; see A. B. Carlson), communicationsystems: An introduction to signal and noise in electricalcommunication, 2 Edition (MaGraw-Hill, New York 1975)

[0004] These concepts have been used extensively in designing manyelectronic devices. For example the lock-in amplifier is used routinelyin many microscopic and tomographic systems, see “Kyuman Cho, David L.Mazzoni and Cristopher C. Davis “Measuring of the local slope of thesurface by vibrating-sample heterodyne interferometery: new method inscanning microscopy, Kyuman Cho, David L. Mazzoni and Cristopher C.Davis)(for as a data acquisition tool, further they are often used inpulling the signal which is embedded in very high noise environment(reference in noise reduction within signals) (M. L.Mead, Lock inamplifier: Principles and applications, (Peregrinus, London 1983).Lock-in detection is also used in controlling machine vibrations, andcomponents within servo systems for tracking CD, DVD and magneto-opticsdisk; references problems of tracking: Casimer Maurice DeCusatis,Lawrence Jacobowitz, “Active Tracking system for optical disk storage,”U.S. Pat. No. 5,793,718. See also Hubert Song et al. Non-contactservotrack writing with phase sensitive detection,” U.S. Pat. No.5,991,112. Time integrative correlators are used in pattern recognitiondevices; e.g. applications involved in identifying a specific opticalbit pattern for header recognition or code-division demultiplexing, ordata base search in high speed optical communication systems or software applications; See Jun Shan (Optical bit pattern recognition by usedynamic grating in erbium doped fiber) Optics letters, Volume 22,1757-1759 (1997) Frequency and time-division, base band demodulators arealso some of the most important components used for constructingtelecommunications systems, networking, cable TVs. See A. B. Carlson,communication systems: An introduction to signal and noise in Electricalcommunication, 2 Edition (MaCraw-Hill, New York 1975).

[0005] In the recent years much attention has been devoted to the use ofwavelength division demultiplexer as one of the main components fortelecommunication systems base on fiber optics. See for example OpticalNetworking Volume 1 January 2000). See also the following U.S. patents:Optical Add-Drop multiplexer compatible with very dense WDM opticalcommunication systems. U.S. Pat. No. 5,982,518 Nov. 9, 1999; Li“Wavelength and Bandwidth tuneable optical system,” U.S. Pat. No.5,841,918. This patent discloses a tunable Bragg cell; see also DanielJ. Fritz, Timothy J. Bailey and Mass Gary, “All Fibre wavelengthselective optical switch,” U.S. Pat. No. 5,446,809

[0006] Wavelength division demultiplexing not only important fortelecommunication but it has significant applications in other areasincluding biomedical applications, remote sensing, multispectra andhyperspectra pattern recognition and fiber sensors. Wavelength divisiondemultiplexers can employ a Fabry-Perort interferometer, including MEMSstructures, Bragg Grating either in fiber, volume holographic materials,or fabricated structure for layers of Electro-optic materials, and aMach_Zender interferometer. See the following material in OpticalSociety of America: Handbook of Optics, volume I and II. For enhancingthe capability of transferring the data in telecommunication systems,most recently it was proposed to combine either wavelength divisionmultiplexing (WDM), with either time (TDM) or frequency multiplexing(FDM). In the receiving end it was proposed that the wavelengthdemultiplexing is done optically and time or the frequency divisiondemultiplexing is done electronically.

[0007] I believe that up until now, no one optical device is present inthe prior art which can do both of these operations simultaneously. Iintroduce a new device concept herein that can be utilized for combiningboth WDM and FDM or TDM demultiplexing on the same device. I name thenew device HTWDM (heterodyne time wavelength division demultiplexing),because the new device not only combines WDM with FDM or TDM, but it cancombine other homodyne detection functionality with wavelength divisiondemultiplexing functionality. In more general terms my invention cancombines K-vector demultiplixing with heterodyne detection (k vectordivision demulteplixing will be illustrated further through the text ofthis invention). This combined functionality has enormous significancefor many applications.

[0008] I introduce herein a general concept for homodyne and heterodynedetection based on K-vector tunable optical cells. An importantapplication is use of the optical cells as wavelength-divisiondemultiplexers (or in more general terms K vector divisiondemultiplexers and mixing for homodyne heterodyne detection or timedivision demultiplexing will be performed in accordance with the presentpreferred inventive emdodiments on a single optical component. Thiscomponent can operate as a low pass filter if the modulation is veryfast. This is in contrast with the distributed Bragg reflector laserstructure of U.S. Pat. No. 5,020,153 of Choa et al. whose invention islimited to WDM (not K-vector demultiplixing) and heterodyne detection,without any consideration for time division demultiplixing. Further inthe Choa patent, each of the operations of WDM and heterodyne detectionwere performed in separate components within the integrated device. TheChao grating was used for WDM, whereas the heterodyne signal detectionwas produced by mixing the signal being detected with an external beatsignal. In contrast with Chao, who discloses using distributed bragggrating within his device, the K vector selector can take numerous formsas will be illustrated. Thus the present invention can have numerousapplication in variety of areas ranges from telecommunication, trackingin CD and DVD, fluorescent microscopy; see M. Schrader and S, W. well,S. W. Hell, H. T. M. Van der Voort, “Three-dimensional super-resolutionwith 4-PI-confocal microscopes using image restoration,” Journal ofapplied physics, 84, 4033-4041 (1998) or in Foliage averaging; see Part1: Foliage Attention and Back scatters Analysis of SAR images, J. G.Fleischman, S. Ayasli, E. M. Adams, D. R. Gosselin. IEEE transaction onaerospace and electronic systems, Vol.32, No 1 January 1996 P 135-144;or for applications in Lidar (light wave radar); see J. G. Fleischman,S. Ayasli, E. M. Adams, D. R. Gosselin .Part III: Multi channel Whitenedof SAR imagery IEEE transaction on aerospace and electronic systems,Vol. 32, No 1 January 1996 P 156-164). In this invention also I proposea gratings to be tunable over wide range, these grating can beintegrated within the structure of distributed feed back laser orvertical cavity lasers for enhancing the range of tunabiliy. It can alsoserve as part of add/drop demultiplexer. Other uses of the presentinvention include microscopic and tomographic sytems, multispectra andhyperspectra pattern recognition, non-destructive testing instruments,atmospheric turbulence correction devices, remote sensing systems andvelocity measuring devices.

[0009] The significance of the present invention in connection withvarious applications can be understood as follows: (1) InTelecommunication for increasing the channel capacity of LAN (Local areanet work and WAN (wild area net work), TV Cables, Telemetry systems. (2)In all forms of homodyne and heterodyne microscopy and tomographyimaging for enhancing sensitivity, which can be achieved by averagingthe measurement at various wavelengths. (3) In nondestructive testing,for controlling the operation of several machines, in which eachwavelength is utilized to probe the operation of one machine. (4) Inhigh precision Lidar probing and velocimetry which may be achieved viaaveraging the homodyne measurement over several wavelengths (5). Datafusion for multispectra and heyperspectra pattern recognition (6).Fluorescent microscopy and tomography (7) In the last three (4,5,6) byperforming spectroscopic correlation as what have been explained in myprevious patent on medical diagnostics (7). In atmospheric turbulencecorrection providung diversity in measuring the atmospheric aberrationat different wavelengths and for CD and DVD applications for the purposeof Pick-up and tracking and switching on different drive, in which a onewavelength is used to read each drive. (8) It can also serve as part ofan add/drop demultiplexer or (9) as components within the optical MODEM.

[0010] The combination of wavelength division demultiplexing andhomodyne detection can be done in a variety of architectures dependingupon the specific application and need. It can be structures from onecell, from combinations of fiber tunable cells, volume tunable cells,volume and fiber tunable cells, array of tunable cells, in aninterconnect within a network architecture. This architecture can beused within WAN and LAN networking using all the well known topologiessuch as Bus, Tree, Ring Star; see “Local & metropolitan Area Network”,William Stallings, fifth edition, Prentice Hall 1997). Or can beintegrated on one substrate. For example, for telecommunicationapplications or endescopic applications, one would more naturallyconsider the possibility of using fiber optical devices, or micromachined devices such as MEMS. For imaging purposes such as parallelmicroscopy, tomography, atmospheric turbulence correction one wouldconsider the possibility of using volume devices or arrays ofmicromachined tunable filters. For conventional microscopy as well asfor reading, writing, and tracking purposes of CD, DVD andmagneto-optics, we will introduce a new holographic tunable cell design.This tunable cell should have ability of focusing light as small as 10nm. This should provide, for the first time, an optical microscopicdesign (not a near field optical microscopy design) which can detectobjects in the atomic level scale, while the tunable cell will functionsimultaneously as a probe as well as the diagnostics tool. If a similardesign is used for optical data storage, then this tunable cell shouldallow recording 10⁵ M bite /cm², with ability to function simultaneouslyas part of the known servo system for tracking and focusing. Thefeasibility of conjunction of this focusing device with other tunableelement is also possible.

[0011] MEMS cells are the only tunable cells which have relatively wideranges of tunability. However, MEMS are slow and mechanically unstable,and can't be used for TDM or hetrodyne detection with very fastmodulation. Therefore we also introduce a general approach forfabrication of tunable gratings over a large bandwidth of wavelengths;so that tunable gratings are used over wide ranges in the presentinvention. While a variety of tunable cells can be used in the presentinvention, a preferred cell is based on Bragg gratings, which can notonly combine wavelength demultiplexing with various homodynefunctionalities, but in an analagous way (according to the Kogelnictheory) it can combine all forms of holographic demultiplexeing(Angular, Rotational, Shift, wavelength or their combination) with allthe various homodyne functionalities and TDM. Examples to be consideredinvolve phase sensitive detection combined with deflection sensitivity,which is a very important functionality for the optical microscopy, Alsothe combination of routing with time-division demultiplixing can beaccomplished with the present invention.

[0012] As known in the field of holography and electro magnetic theory,either change in the wavelength or the beam direction, are considered aschanges in the k-vector of the beam. In holography, grating efficiencyis analogously sensitive in the K-vector variation, regardless ofwhether the variation comes from a change in the wavelength or the beampropagation direction or their combination. This should make anygratings devices based which can be implemented with wavelengthvariation also can be implemented with beam propagation directionvariation or the combination.

[0013] The invention of K-wave selector based on thick Bragg gratings orholography can also have addition functionalities: (1) Spatial noisefiltering ability. A significant feature for all diffusive microscopyand tomography as well as optical pick-up in multilayred data storage(2) wavefront de-encryption, a significant feature for atmosphericturbulence correction, and parallel microscopy and tomography. Wavefrontdeflection sensitivity is essential for numerous applications discussedherein such as microscopy, tomography, profilometry).

SUMMARY OF PREFERRED EMBODIMENTS OF THE INVETION

[0014] The term “K-vector” along with Bragg matching, is discussed inone of the most fundamental papers in holography by Kogelnik, (H.Kogelnik Bell Syst Tec.J 48,2909-2947 (1969). See for example, U.S. Pat.No. 5,438,439 to Mok et al at col. 4 among others. The length of thevector indicates wavelength and the orientation of the vector indicatesbeam direction. Either change in the input wavelength or in the beamdirection represents a detectable variation in the K-vector of the inputsignal. The invention involves the use of tunable cells comprising forexample: Bragg cells, Fabry-Perot etalons and it MEMS version,interferometers, holographic multiplexers such as (wavelengthmultiplexers, angular multiplexers, rotation multiplixers or theircombination). These devices can operate in the transmissive mode wherelight is transmitted through the device or in the reflective mode, wherethe light is further transmitted by being reflected off of the device.Some applications shown in detail below, involve telecommunication, CDand DVD optical pickup devices, and microscopy. The Bragg cell iscurrently the preferred “K-vector selector” for most of theseapplications, and the cell tuning source will preferably comprise atuning cell control voltage source for producing an electrical controlsignal having a DC component and an incremental AC component. The DCcomponent can select desired wavelengths or (K-vector and/or angle ofincidence) of incoming light beams and the AC incremental component caninitiate hetrodyne detection of a desired frequency, amplitude or phasemodulated light beam by hetrodyning the AC component with the appliedmodulated light beam signal, and a time integrating CCD camera cancompletely retrieve the detected beam modulations representing thetransmitted intelligence. In the combined TDM and WDM (or K wavevectormultiplixing) arrangement, the AC component turns the cell, preferably aBragg cell on periodically during the time slots being demultiplexed ordetected. In all embodiments, the AC component functions as a signaldetector.

[0015] The invention employs a preferred method of demultiplexing agroup of intelligence bearing light signals having different K-vectorsand modulation K-vectors including the steps of: providing a K-vectorselector (e.g. Bragg cell, volume hologram, interferometer) forsimultaneously performing K-vector (e.g. wavelength) divisiondemultiplexing and hetrodyne detection of selected K-vector modulated(e.g. frequency, phase or angle modulated) intelligence bearing lightsignals from the group of incoming intelligence bearing light signals,and applying an electrical control voltage (or appropriate tuning sourcesuch as stress, temperature, magnetic force, and mechanical motion)across the K-vector selector having a DC component for selectivelytuning the K-vector selector to a selected transmission K-vectorcorresponding to a particular value of the DC component for causing theK-vector selector to transmit the light signal having such a selectedtransmission K-vector (e.g. wavelength), together with an AC componenthaving a temporal signal for selectively producing heterodyne detectionon the selected signal, and time integrating the resulting signal tocomplete demodulation of the selected signal.

[0016] A preferred embodiment of the invention is shown in FIG. 5Bwherein a single high resolution holographic pickup is provided in asingle reader which can read both a CD 610 and DVD 608 optical recordingmedium. An electrical tuning control signal source 614 applies both a DCand an AC signal to a tunable Bragg cell holographic element 612, whichAC signal is phase locked with respect to the fundamental repetitionfrequency of the recorded data on the CD or DVD to produce accuratetracking. A special high resolution holographic lens is recorded withinthe Bragg cell that focuses the light signals read off of the opticalstorage mediums upon a pickup detector means 616, and its focal lengthis varied to read a selected CD and or DVD from a group of CDs or DVDsin response to changes in the DC applied to the holographic elementBragg cell 612. The holographic lens within the Bragg cell is formed byan interference pattern produced by interfering light emitted from thetip of a one micron optical fiber 500 in FIG. 4, and a plane broad lightbeam from plane wave source 506.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The various features of the invention will become more apparentupon study of the following detailed description, taken in conjunctionwith the drawings in which:

[0018]FIG. 1. shows a tunable cell homodyne and heterodyne detector;

[0019]FIG. 2(a) shows a schematic diagram of simultaneous WDM andhomodyne heterodyne detector implemented via electro-optic modulatorwhich is sandwiched within the etalon of FIG. 2(B) but in this case theetalon and the electro-optic modulator are cascaded;

[0020]FIG. 3. shows (a) parallel (b) the serial architectures forcombining wavelength division demultiplexers and homodyne heterodynedetectors utilizing conjunction devices;

[0021]FIG. 4. illustrates fabrication of holographic lens elements withultra high focusing capability;

[0022]FIG. 5.(a) shows architecture for microscope multi-head opticalpickups for very high resolution;

[0023]5(b) shows modified architecture, which is suitable for an opticpick-up for CD and DVD;

[0024] FIGS. 6(a) and 6(b) show different designs for a multi-headpick-up for the optical microscope;

[0025]FIG. 7: show a tune multiplex architecture for fabrication ofextended range enhanced strength tunable Bragg cells (a) usinginterference between two beams (b) multiplexing via lithographicprojection masks of gratings.

[0026]FIG. 8(a) is a schematic diagram of a prior art Hartmann sensorfor wavefront measurement; 8(b) schematically illustrates a tunablevolume based Bragg grating sensor for wavefront measurement anddetection; and

[0027] FIGS. 9(a) and 9(b) illustrate how WDM and TDM may be combinedfor various operations such as, for example, fiber optic datatransmission or spread spectrum transmission in accordance with theinvention.

[0028]FIG. 10 illustrates the configuration of AND, spread spectrumconfiguration for secured data transfer.

[0029]FIG. 11. Shows a k-vector selector space division router.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0030]FIG. 1 shows a tunable cell homodyne and heterodyne detector,employing a tunable cell. Let us assume for the sake of simplicity thatthe tunable cell is an Electro-optic modulator 101, which is driven byexternally modulating tuning voltage source 103 and let us assume thatthe incident beam 105 on the electro-optic modulator 101 is alsomodulated. The light, transmitted through this electro-optic modulator,is collected through a time integrative device such as slow responsephoto-detector 107. This device is basically acting as homodyne andheterodyne detector. The mixing occur as result of transmission of themodulated beam from the electro-optic modulator. The time-integration isa consequence of detection with a photodetector which has slow responsetime together with band pass filter 108. In this embodiment of theinvention, and in those that follow, it is not necessary that the tuningcell be an electro-optic modulator, it can comprise an acousto-opticmodulator, elasto-optic modulator, thermal modulator, piezoelectricmodulator, self-electro-optic modulation, even mechanical (see K. JEbeling, Integrated Opto-electronics, Waveguide Optics Photonicssemicondoctor Springer-Verlag, p 481-484) with the appropriate tuningsource. For example in an elasto-optic modulator, the tuning controlsource should be a stress rather than a control voltage, while for theself Electro-optic effect, the tuning source is a modulated opticalbeam, the modulated beam creates a corresponding variation in the indexof modulation according to Stak effect, Franz-Keldysh (see K. J Ebeling,Integrated Opto-electronics, Waveguide Optics Photonics semicondoctorSpringer-Verlag, p 453)effect. The last form of the tunable cellhomdyne-heterodyne detector might have application in wirelesstelecommunication.

[0031] The combining of wavelength division demultiplexing withhomodyne/hetrodyne detection can be performed using either a one-cellapproach or multiple cell approach. If the tuning cell has a strongtunability, then such a combination can be done with one cell, if thetuning cell has a very weak tunability, then multiple cells are needed.Near the end of the specification, I will illustrate how to convert acell from small tunability into a large tunability.

[0032] It is possible to realize a device which can functionsimultaneously as wavelength division demultiplixing and frequencymixer. Most important interferometers such as Mach-ZechenderFabry-Perot, Bragg grating (in fiber, volume materials, structured stackof Electro optic material such as GaAs GaAlAs) can be used for thispurpose. To achieve the two functionalities simultaneously, the tuningsource has two components Dc bias component and an AC modulationcomponent. The DC bias component is the one which is responsible forselecting the wavelength, that is, it is the one which is responsiblefor wavelength-division demultiplixing. The AC modulated component isthe one responsible for achieving homodyne detection and time divisiondemulteplixing and other sub-functionality to be explained.

[0033]FIG. 2(a) shows a schematic diagram of a heterodyne wavelengthdivision demultiplexing detector implemented via electro-optic modulator200 which is sandwiched within an etalon (Fabry-Perot) 202 andexternally modulated via a tuning control voltage source 204. In thisscheme, a beam 206 (consisting of a combination of several beams, eachof the beams is at it own wavelength and its time modulation), isincident on the sandwiched etalon. The transmitted light from the etalonis detected via time integrative detector 208 and bandpass filter 209.Importantly, this single device functions simultaneously aswavelength-division demultiplexer and homodyne heterodyne detector.

[0034] Assume that our driving voltage is V=Vo+v f(t), where Vo is aconstant bias and f is a periodical function. Then for each value of Vo,a certain wavelength will be transmitted (or reflected in a reflectedmode device). On the other hand the periodical component of the voltagedemodulates a selected signal according to f(t). Because each of theinput beams at a certain wavelength is modulated, then the tuned cellacts as a mixer between the input beam and variable component of thevoltage. The output detector with its supporting electronics performsthe time-integration. For cells with very narrow band filtering and highmodulation frequency of the tuning and the input signals, the cell canalso act as low pass filter or time averaging device. This means thatthe process can be all optical, and there is no need for conversion toelectronic signals.

[0035] A disadvantage in using the above approach is that one my need tosacrifice wavelength selectivity for introducing several beams modulatedwith different frequency modulations. Another alternative, illustratedin FIG. 2b, is to cascade the electro-optic modulator 214 with theFabrey-Perot etalon 212, which could be an interferometer. The DC outputcomponent from the tuning voltage source 216 passes through low passfilter 218 and is used to drive the etalon for selection the wavelength.The AC component from the voltage source passes through high pass filter220 and is used to drive the electro-optic modulator 214 in order toachieve homodyne and heterodyne detection. In this embodiment, theetalon and EO modulator together comprise a single K-vector selectormentioned in the invention summary photodetector 222 and BPF 223function as in the prior figures. For an etalon or other WDM device withvery narrow band filtering and high modulation frequency, the etalon canalso act as low pass filter or time averaging device. However, for doingso the etalon 212 should be placed after the electro-optic modulator214.

[0036] Incidentally, the HWDM can be fabricated as one structure. Oneface of the electro-optic modulator can be shared with the etalon. Iffor example, one face of the etalon was a micro-machined membrane(References on tunable Fabry-Perote J. Peerling, A. Dehe, A. Vogt, M.Tilsch, C. Hebeler, F. Langenhan, P. Meissner “Long ResonatorMiromachined Tunabel GaAs_AlAs Fabry-Perot Filter,” IEEE PhotonicTechnology Letter. Vol.9. No 9 September 1997 (2)E. C. Vail, et, al.,GaAs micromachined widely tuneable Fabry-Perot filter” Electron.Letter., Vol. 32, P. 1888,1996), then the whole voltage including V(t),can be applied to the membrane with no need for the low pass filter 223,as low pass filtering is achieved because the micro machined membranewill not be able to follow the fast temporal modulation of the opticalsignal. A SEED, or self electro-optic effect devices such as a pnjunction, and which can be driven optically or electrically, can alsofunction as a light detector. This should open the possibility ofintegrating the WDM, the modulator and the detector only on onecomponent.. Regarding SEEDS, see K. J Ebeling, IntegratedOpto-electronics, Waveguide Optics Photonics semicondoctorSpringer-Verlag, p 481-484.

[0037] Another elegant implementation is to provide a Bragg grating, onehalf of it being chirped, and is tuned for selecting the wavelength, theother half of it is not chirped and can be used for homodyne heterodynedetection. Thus, the number of various implementations can be many,depending upon what kind of cells well be used for WDM and what kindwill be used for time modulation. If this device functionality isreversed then it can act as modulator which can combine more than oneform of modulation. This modulator can be used as a part of multiplixer,which combine TDM and FDM and WDM.

[0038] For example, the combination of the three forms of modulation canbe realised as follows. Instead of selecting a constant Vo, In FIG.2(B), Vo should be replaced by binary digital modulating signal, onelevel of the binary digital signal lets the etalon to transmit a certainwavelength, and other level off set any wavelength transmission, ortransmit other wavelength which can be filtered out. While theElectro-optic modulator still function as frequency modulator, otherforms of modulation such as phase or amplitude modulation can bereplaced by frequency modulation.

[0039] In cases where the single tunable cell is weak, that is itdoesn't have enough tunability throughout the desired range ofwavelengths to be demultiplexed, then the single tuning cellarrangements of FIGS. 1 and 2 should be duplicated by cascaded orparallel plural cell structures in the manner illustrated in FIGS. 3aand 3 b.

[0040]FIGS. 3a and 3 b show the (A) parallel (B) serial architecture.The tunable cells are connected through conjunction devices, theseconjunction devices can be either fibers, lenses, holographic elementswith interconnect capability, in order to allow for whatever combinationof tunable cells are desired for a specific design or need. Let assumefor the simplicity at this stage that the conjunction devices simply arefiber wires, and the tunable cells are Bragg gratings. Several incomingcarriers beams 301 carry information in the form of time modulation,frequency modulation of amplitude modulation. This beam is separated forn channels (in the drawing we show only 3 using the beam splitter 303.The light from the beamsplitter is transferred through the conjunctiondevices 305 to a set of tunable cells 307 in which each corresponds to acertain wavelength. Each of the tunable cells are modulated with anassociated tuning source 309 in order to demodulate the signal via theset of time integrative devices 311, which consist of low pass filterwith detector.

[0041] The device in FIG. 3(b) involves summation of several carriersbeams 313 coming through a fiber from a remote distance. Each of thebeams carries information in the form of time modulation, frequencymodulation, or amplitude modulation; these beam are received byreceiving device 315e.g a fiber. The light is transmitted through thereceiving device, and through several cascaded tunable cells, here weshow only two tunable cells 317 and 323. These tunable cells areconnected through a conjunction devices 321, (here we show only one),each tuning cell is tuned to work at certain wavelength and it modulatedby its own tuning frequency to demodulate the signal. All thedemodulated signals are received by the wavelength divisiondemultiplixer 327 then to a time integrative correlator 400 whichconsist of detector 401 and band pass filter 402. These devices aresuitable as part of a telecommunication system or as a part of fibersensing device. However, because the conjunction devices can be lenses,or beam interconnect holograms, these devices can be designed to suitedifferent application, as we will show next.

[0042] Conjunction devices can be utilized for transferring light fromfiber tunable cells into volume tunable cells using Fourier transformlenses, and this design can be reversed. Also, the conjunction devicecan be hologram which can connect one beam to a number of beams indifferent sides of the hologram, Many architectures can employ thetunable cells in various ways. In both FIG. 3 arrangements, for veryfast modulation, the tunable cell or the WDM can act as a band passfilter.

[0043] Regarding tunable optical pick-ups for optical storage andmicroscopy, several microscopes and tomographies have been reported inthe literature, some of these microscopies are based on Doppler shift,others are based on deflection of the beam from the exact direction suchas ultrasonic. Implementation of the scanning tomographic acousticmicroscope for Multiple-Angle tomography Richard Y. Chiao and Hua Lee,PP 499-509, Acoustical Imaging Edited by Helmunt Ermert and Hans-peterHaijes Acoustical Imaging Vol 19), photothermal (reference onphotothermal microscopy) (Photothermal refraction for scanning lasermicroscopy, Dean S. Burgi, Thomas G. Nolan, Jon a. Risfelt, Norman J.Dovichi, Optical Engineering, 756-758 (1984)), atomic force microcopiesreference atomic force microcopies (scanning probe microscopy fortesting ultrafast electronic devices, A. S Hou, B. A. Nechay,F. Ho, D.M. Bollm, optical and quantum electronics, 28, 819-814 (1996),profilometery (reference on profilometrey)(measurment of the local slopeof a suraface by vibrating-sample heterodyne interferometery: a newmethod for scanning microscopy, Kyuman cho, David L. Mazzoni andChristopher C. Davis, Opt. Letts, 18, 232-234, 1993) et, st and. Othermicrocopies rely on the fluorescent emission of light from cells ormaterials; see fluorescent atomic microcopy(M. Schader and S. W. Hell,H. T. M. van der Voort “Three-dimensional super-resolution with a4Pi-confocal microscopy using image restoration,” Journal of appliedphysics 84, 4033-. And some microcopies rely on combination of theabove. For performing all these microcopies some form of homodyne orheterodyne detector may be employed.

[0044] Tracking and focusing elements in optical storage devices canemploy some form of homodyne detector. See “Non-contact servo trackwriting with phase sensitive detection,” U.S. Pat. No. 5,991,112 issuedto Song et al.. We introduce herein a tunable cell based optical pickup; this optical pick up is constructed holographically, on tunableholographic materials such as photorefractive materials. It can beconstructed in interconnect gemetries connecting one beam to anotherbeam, in what ever form of multiplexing from wavelength multiplexing,angular multiplexing or tunable effect multiplexing. This should openthe possibility of having optical pick-up devices for scanning differentpoint on the target, or different depths, or it should allow ability ofoptical pick-up with different wavelengths in different locations anddifferent depths. Furthermore, the holographic construction of suchoptical pick-up devices should permit construction of optical pick-updevices with very sharp focussing capability. It is well known inmicroscopy that the resolution is limited by the ability of opticalcomponents to focus beams (the diffraction limit of optics). The samelimitation also applies to writing information on optical data storagedevices. In optical microscopy, to avoid this limitation, it has beensuggested to perform microscopy in the near field. In this case ananoscale fiber tip is used to replaces the optical pick-up. Using thisapproach it was possible performing microscopy in the sub-micron regime.Most recently there were some reports on optical microscopy within thenanoscale regime (combination between near field microscopy withhomodyne microscopy). The draw back in near field microscopy is that itcan't be used on living organs or deep tissues in vivo.

[0045] For providing an optical pick up with very high resolution, Iprovide a holographic lens element which can be produced frominterference between a beam originated from point source 500 of FIG. 4,and another beam from quasi-plane wave beam source 506, on a Bragggrating holographic element 504, all shown in FIG. 4. For extraordinaryhigh resolution I suggest that the point source of light emerges from afiber tip, or other very small transmissive, or reflective element, Mostrecently there were reports on fiber tips of 10 nm diameter opticalfiber tips. See Shuji Mononobe and Motoichi Ohtsu “Development of afiber fabrication application oriented near field probes.” IEEE photonictechnology letter. Vol 10, No 1 January 1998. For extra high resolutionand to avoid the diffraction limit of optics due to aperture size Isuggest eliminating an optical lens or element 502 entirely. For thoseholographic materials permitting recording of such a hologram, then thisshould allow construction of optical pick-ups for performing microscopyin the atomic level scale, and recording information in the opticalstorage in the atomic scale level. For example in one cm² using 10 nmoptical pick-up, this should allow recording nearly 10² Gpite/cm².;nearly one hundred times the current density in use. There are someholographic material, which are tunable. For example LiNbO3 and KnBO₃.isone of the holographic materials which is tunable via the Electro-opticeffect. If the holographic material is tunable, then the optical pick-upcan be made to function also as homodyne and heterodyne detector byadding the tuning source 508 during the pick-up process (forphotorefractive material the tuning source is electrical). However, foravoiding anistropy I recommend that the tunable cell to be separatedfrom the holographic lens shown in FIG. 6(B)

[0046] Thus, it is an important feature of the present invention toprovide a method of producing at least one, and generally an array ornumber of non-diffraction limited holographic lenses comprising thesteps of: interfering a point source of light from the tip of a singlevery narrow optical fiber, preferably having a diameter in the nanoscaleregion, e.g. ten nanometers, with a plane wave of light; and recordingthe resulting interference pattern on a holographic element, which canbe the K-vector selector.. This process is repeated over and over untilan array of holographic lenses of a desired number are produced. Theselenses are extremely useful in the microscopic imaging systems and CD,DVD optical readers to be described below. Of course, for eachside-by-side lens to be recorded, the fiber tip is displaced anappropriate distance relative to the holographic element.

[0047] Importantly, in FIG. 5a discussed below, numerous point sourcesare projected at the sample by an array of holographic lens elements forultra-high resolution, each element being constructed as described andschematically illustrated in FIG. 4. Such high resolution lensconstruction is also employed in optical pickups and DVDs discussedbelow. While the prior art holographic elements were micro fabricated,here we propose building it using holographic fixing approaches. Thehigh resolution holographic lens discussed above based on fixingapproach has advantages over a holographic element based on the microfabricated one. These advantages are (1) The ultrahigh resolution as aresult of interference between light coming from micro tips (2)de-encryption of the information using a thick holographic element (3)The ability of the holographic element to act as k-wave vectordemuliplexer as well as a homodyne detector.(4) The ability to work asspatial noise filter

[0048] As shown by the following publications and patents, holographicelements have been used with CD and DVD optical pickups; see for examplethe following references: (1)Akio Yoshikawa, Hidenyuki Nakanishi, KunioItoh, Takeshi Yamazaki, Tetsuo Komino, and Toru Musha. IEEE Transcationon componnents, Packaging, And Manufactring Technology. Part, B. Vol.18. No 2. May (245-249) 1995.;(2)Shinya Hasegawa “Compact sizemagneto-optical head with a hologram and a beam splitting means,” “U.S.Pat. No., 5,751,682;(3)Kazushi Mori, Atsushi Tajiri, Yasuaki Inoue“Three beams generating diffraction grating, transmission type holograpmoptical element and optical pickup appaartus using the same,”;. U.S.Pat. No. 5,717,674 (4) Shinya Hasegawa “Optical Head for optical diskdrive,” U.S. Pat. No. 5,708,644 Zu-Wen Chao, Tsung-ming Yan, Shin TerTsai, Jau-Jiu Ju, Pei-Yih Liu “Single-lense optical pick-up head foraccessing a DVD and CD Disk by switching between two optical states,”U.S. Pat. No. 5,748,602.

[0049] Most optical pick ups for writing and reading data on opticaldata storage devices have three ports, one for reading the information,and two for servo systems; one for focusing the pick up correctly andthe other for keeping the optical pick-up in track FIG. 5(b). Usually aphase sensitive detector is a part of the servo system. The opticalpick-ups can be constructed in interconnect and multiplexed (wavelengthand angular) geometries, in order to have as many as output port andreadout heads. For example, in most optical data storage systems threeoutput ports and one head for reading the information are employed. Oneof the out ports is utilized for reading the information the other twofor the servo system for purpose of accurate tracking and focussing.There were also some reports on optical pick-ups with two-readout head;see (Zu-Wen Chao, Tsung-ming Yan, Shin Ter Tsai, Jau-Jiu Ju, Pei-Yih Liu“Single-lens optical pick-up head for accessing a DVD and CD Disk byswitching between two optical states,” U.S. Pat. No. 5,748,602, one forreading CD and other one for reading the DVD. In optical microscopy, itis possible to construct pick-ups with multi-read heads each beinginterconnected with its special port. For fluorescence microscopy it ispossible to construct the pick-up with tuning capability for variouswavelengths. The interconnect can be either in transmission orreflection geometries, If the holographic materials are tunable, thenthe optical pick up can serve as a K-wave selector as well as homodyneand heterodyne detector.

[0050] Ultra-High Resolution Microscopic Embodiments

[0051]FIG. 5(a) shows an optical microscope using a multiple-headoptical pickup made as discussed in connection with FIG. 4, for veryhigh resolution. Such a head can be constructed using a holographicstorage and focusing means 602 for connecting point sources on thesample 600 to point sources on the detector array 606. This opticalpickup herein simultaneously serves as a multi-head pick-up tunable cellthat is driven by the tuning source 604 for performing hetrodyning andcolor selection. If for example the holographic element is LiNbo3, thenwe can use the holographic elements also as a wavegiude for integratingthe detector

[0052] In heterodyne optical microscopy, the specimen or its associateprobe or associated probe membrane is often oscillating. These featuresare essentially employed in most forms for microcopies. Light scatteredfrom oscillating objects is usually associated with Doppler shift aswell as deviation in the beam orientation, which is essentially a changein the K-vector wavelength. In holographic pick-up systems, this isgoing to change the Bragg conditions and hence the intensity of thetransmitted or reflected light. If the pick-ups also functioning aswavelength division demultiplixer, then it possible to perform Foliageaveraging; see Part 1: Foliage Attention and Back scatters Analysis ofSAR images, J. G. Fleischman, S. Ayasli, E. M. Adams, D. R. Gosselin.IEEE transaction on aerospace and electronic systems, Vol.32, No 1January 1996 P 135-14.

[0053] The microscopic sample 600 is vibrated by vibrator V. The purposeof this vibration is to modulate in time and space the focussed beams,produced by pinpoint light source array 607 projected through theholographic element 602 via beam splitter 605. The holographic elementalso has focusing lenses such as fresnel lenses recorded therein. Thetuning source 604 and the transducer vibrator V are phase lockedtogether by a function generator 603 with phase locked capability, sothat the function generator drives the microscopic sample 600 while theholographic element 602 simultaneously operates as a K-wave vectorhetrodyne detector. The CCD image detector 606 is operating as a timeintegrating device for each focused beam so that microscopy occurs inparallel. The DC level component of the tuning voltage source 604 can bebeneficially adjusted for in turn adjusting various desired wavelengthranges of light for specimen examination as desired by those skilled inthe microscopy art. The AC component is used to perform the hetrodynedetection of retroreflected light scattered out of the sample. Thiscreates a map of the surface roughness and granularity of the sample intwo dimensional data acquisition. The optical microscope pickupapparatus of FIG. 6a is similar to FIG. 5a except that the K-wave vectorselection is done in separate tunable cells 708. The focussed beams 704from holographic element 702 are converted into plane waves by lensarray 706 and are inputted into the tunable cells of cell array 708. Thesample specimen support stage vibrator is phase locked with the tuningsource 712 as in FIG. 5a, and the use of a discreet array of lightsources with the beam splitter is as described in connection with FIG.5a. Such a discreet array of light sources, e.g. 607 in FIG. 5a can beeliminated by the use of a plane wave 724 and beam splitter 723 passingthrough the holographic element and focussed via a microscopic lensarray 718 shown in FIG. 6b; also tuning source 722 is coupled to thetunable cells 721 as in FIG. 6a. FIGS. 6a and 6 b show two differentdesigns for the multi-head pick-up for the optical microscope. In FIG.6(a) the holographic element 702 functions as an interconnect elementbetween point sources on the sample 700 and the point sources at 704 onthe other side of the holographic element. A microlense array 706 isused to convert the point sources of light into plane waves. These planewaves are incident to tunable cell 708, which can be an array of cells,which function simultaneously as wavelength division demultiplexers aswell as homodyne and heterodyne detectors. The tunable cell is drivenvia the tuning source 712..

[0054] The design in FIG. 6A, was illustrated-using a holographic lensto obtain ultra high resolution,.for standard resolution, theholographic lens is not necessity, and simply can be replaced by anarray of lenses with the tunable K-waves-selector

[0055]FIG. 6(b) shows another alternative architecture wherein the pointsources 714 on the sample are interconnected to generate a set of planewaves directed at holographic element 720. A-microlens array 718 is usedfor generating plane waves propagating within the holographic element720, though in general, the structure can be designed without themicro-lens array element through an appropriate interference design ofthe holographic element. The out put from the holographic element 720goes through a tunable cell 721 which functions simultaneously as a WDMand homodyne heterodyne detector. This cell is driven via the tuningsource 722 and a plane wave 724 is directed at the holographic elementvia beam splitter 723.

[0056] CCD 710 a is also provided as before. For the purpose ofcompactness, the tunable cell and the holographic element can be alsointegrated. FIGS. 5a and 6(b) can be modified according to the form ofthe microscopy. For example, in ultrasonic microscopy, the oscillatingsample can be replaced by oscillating membrane overlaying the sample.For implementation of the scanning tomographic acoustic microscope forMultiple-Angle tomography, see Richard Y. Chiao and Hua Lee, PP 499-509,Acoustical Imaging Edited by Helmunt Ermert and Hans-peter HarjesAcoustical Imaging Vol 19). In photothermal microscopy the vibrator canbe replaced by modulated laser beam(Photothermal refraction for scanninglaser microscopy, Dean S. Burgi, Thomas G. Nolan, Jon a. Risfelt, NormanJ. Dovichi, Optical Engineering, 756-758 (1984)). In atomic forcemicroscopy, the vibrator is replaced by fast electrical field modulationof the sample from a Cantilever chip, and the laser beam instead beingscattered out of the sample. It scattered out of the Canilever chip(scanning probe microscopy for testing ultrafast electronic devices, A.S Hou, B. A. Nechay,F. Ho, D. M. Bollm, optical and quantum electronics,28, 819-814 (1996). In fluorescent microscopy a spectrum is emitted formthe sample and hence therefore the K wave selector should function asspectroscopic time integrative correlator; see (M. Schader and S. W.Hell, H. T. M. van der Voort “Three-dimensional super-resolution with a4Pi-confocal microscopy using image restoration,” Journal of appliedphysics 84, 4033, 1999).

[0057] For most microscopes, a phase locked template should be appliedby tuning source 604 to the tunable K wave vector selector, namelyelement 602 in FIG. 5a, or tunable cell 708 in FIG. 6a. This templateshould be locked to the received light via the K vector selector. Thephase locked template can have oscillatory behavior or a bundle offrequencies depending on the form of microscopy. Also, it may be notedthat the phase locked template, which may be used with fluorescentmicroscopy also, may be usable with hyperspectra automatic targetrecognition.

[0058] CD DVD High Resolution Optical Pick-Ups

[0059]FIG. 5(b) shows modified architecture which is suitable for anoptic pick-up for CDs and DVDs. In this case two different point sourcesof light 610 and 608 are provided, each of these point sources isinterconnected through the aforesaid high resolution holographic lenselements in holographic element 612, to three points on detector array616. In this case, the holographic element 612 functions simultaneouslyas a pick-up as well as mixer driven by the tuning source 614. The pointsources of light in the fabrication process can be designed to beoperating in different wavelengths; the holographic element can also bedesigned to switch between two different wavelengths, one to be used forreading a CD point source 610, and other to be used for reading a DVDpoint source 608. Or it can be designed to enable switching to differentfocusing levels in order to be able to read multi-layered data storagemedia, or to read volume data storage. For example if the holographicelement is LiNbO3, then we can use the holographic elements also as awavegiude for integrating the detector.

[0060] The DC voltage component applied by tuning source 614 toholographic element 612 can be used as before to select the wavelengthwhich in turn can produce focussing at point 610, or alternatively at608 to accommodate different CDs or DVDs as indicated in FIG. 5b, or toaccommodate different focal depths, which need not necessarily be of thesame wavelengths. The three detectors of detector array 616 areconventional for CD tracking, focussing and detection as is well known.

[0061] For the purpose of tracking, the aforesaid AC component of thetuning voltage is used to perform phase sensitive detection on thelight, which is reflected off of the data storage medium. The phasesensitive out put should be fed back to a servo system in order toadjust the focussing point as well as the tracking. In the normaloperating condition, the AC tuning component applied to the holographicstorage element 612 should have the same frequency of the light whichreflected off of the CD, DVD data storage media. However, when thepick-up goes out of tracking, the frequency of the light, which isemitted from the data storage media, is changed, or even can go tohigher harmonics. This phase sensitive output signal fundamentalfrequency established by the spacing of the pits on the CD. Thesechanges in the frequencies should make significant changes in the phasesensitive out puts, and these changes can be fed back into the servosystem (not shown here) to readjust the focusing or the beam scanposition on the storage medium being read. For these prior art detailsof tracking adjustments, see U.S. Pat. No. 5,793,718 to DeCusatis, andU.S. Pat. No. 4,385,74 to Wilkinson.

[0062] The holographic element FIG. 5(b) can have severalfunctionalities, (a) it can function as a focusing lens (b) homodyne andheterodyne mixer (c) interconnect element (d) demultiplixer to focus ondifferent focussing depths which also can employ different wavelengths.These functionalities can be carried out by separate components ratherthan by the same component, and in fact can be separated (either in acompletely separate component or in an integrated structure, similar tothe separate component arrangements in FIGS. 6a and 6 b.

[0063] The tuning of the focal length occurs as follow, the holographiclens should be produced so as to focus at different focal depths whenthe read out light changes color as shown in FIG. 5b. The change in theread out color of the holographic lens is controlled via the DCcomponent of the tuning voltage signal applied to the tunable cell. Ifthe holographic lens comprises a thick holographic element, severaladvantages can be had: (a) higher sensitivity to the deviation of thepick-up when goes out of track, (b) high sensitivity in reading theinformation recorded on the data storage medium (c) the possibility ofdesigning lens with variable focussing depth according to thewavelength, (d) possibility of designing a pick-up with ultra highresolution as mention above for higher data storage and/or smaller CDreaders, though for this feature it is not necessary that theholographic lens to be produced having a thick holographic element, butcould be recorded in accordance with the fiber tip feature of thepresent invention shown in FIG. 5. However, the optical pickup of thepresent invention could still be beneficial if a standard lens or amicro-fabricated holographic lens is employed, rather than these desiredenhancements.

[0064] The present invention based on thick Bragg gratings orholographic elements can have addition functionalities:

[0065] (1) Spatial noise filtering ability; a significant feature fordiffusive microscopy and tomography as well as optical pick-up inmultilayred and volume data storage

[0066] (2) Wavefront measurement or de-encryption, a significant featurefor atmospheric turbulence correction.

[0067] (3) Wavefront deflection sensitivity which is significant formicrocopy, tomography, profilometry.

[0068] In addition, all of the tunable K-vector demultiplexers, whichneed not be relatively thick, also have the following functionality's

[0069] (4) Phase sensitive detection: For example if the input beams aremodulated with same frequency, as the tuning source, then the outputfrom the detector should be dependent of the difference of the phasemodulation of the input and the tuning source.

[0070] (5) Frequency converter: If the input beams and the tuning sourceare modulate with frequencies which are slightly different, then, theoutput from the detector should have signal which dependent on thefrequency difference of the input beam and the modulating source.

[0071] (6) Base band demodulator: If both the input beams and the tuningsource have same carrier frequency. Further if either one of the tuningsource or input beams is also base band modulated, then the output fromeach the K-wave vector selector should be base band signal.

[0072] (7) frequency division demultiplexing: If the input beam consistof superposition of several beams, each beam with its is own frequency,and further if the tuning source is tuned to one of the frequencies ofthe input beam, then the corresponding modulation in the input will beenhanced at the out put for producing frequency division demultiplexing.

[0073] (8) Time integrative correlator: If the input beam is modulatedvia a certain template and tuning source is modulated with anothertemplate, then the out put from the detector should correspond to thetime integrative correlation between the two templates. This timeintegrative correlation can operate either on digital or analog signal.Correlation of digital signals for example is suitable for data gramrecognition in the internet.

[0074] (9) Spectroscopic correlator: Spectroscopic correlation is verysimilar to time correlation. In this case the input template is aspectrum which is variable with time, and the transmissivity of the WDMor K-wave selector is tuned in time (via the tuning source) to match acertain spectrum. If the tuning source modulates the WDM transmissivity(or reflectivity) to match the input spectrum, then we can sayspectroscopic correlation has been achieved. If the tuning does notmatch the variation in the input spectrum, then we can say that crosscorrelation has been achieved.

[0075] (10) The AND Logic Gate: In this case the incoming signal isdigital binary information, and the applied AC voltage on the K waveselector is also binary synchronous with the received signal, then thedevice is acting simultaneously as K-wave selector and an AND logicgate. This feature might have many application include datagramprocessing in telecommunications or other applications in opticalcomputing

[0076] Regarding strengthening tunability, that is widening thefrequency or wavelength range response, one of the main features of thepresent invention, is having a tunable cell, which can actsimultaneously as WD Multiplexer and mixer for homodyne and heterodynedetection or other operation such as the AND gate. As I indicatedpreviously, since most candidate materials do not have large dynamicrange of tunability, then a technique is desired for expanding thetuning range.

[0077] One of the main methods nowadays for producing WDM is to use theBragg grating. WDM has been produced using both in volume holographicmaterials, fibers and stacks of electo-optic materials using standardtechniques of thin films deposition. In these cases the tunability isnot large and is insufficient to permit one cell to have tunability overa large dynamic range. Only recently some reports were made availableproducing a tunable Bragg grating in fibers; See for eaxmple, (1)demonstration of thermally-polled electro-optically tunable fiber Bragggrating (OSA) Meeting San Clara, Calif. (1999) Paper W13) (2)H. Mavoori,S. Jin, R. P Espindola and T. A. Strasser. “Enhanced thermal andmagnetic actuation for broad-range tuning of fiber Bragg grating-basereconfigurable add-drop devices,” Opt. Letters. 24, 714-716 (1999). Inone of the reports they used thermal and magnetic tuning sources, whichare not flexible.

[0078] Therefore, I propose herein a method for making a Bragg gratingto be tunable over a large dynamic range of wavelengths. I call thisapproach tune multiplexing. In the tuning multiplexing shown in FIG. 7a,a tuning source DC tuning signal, preferably a voltage, is applied bytuning source 800 across the material of holographic element 802, whilea Bragg grating correspond to a certain wavelength in accordance withthe Bragg condition, is recorded in the material.. In FIG. 7(A), we canrecord the gratings via interference between two beams 801 and 803.After recording a first grating, a new appropriate DC bias is applied bythe tuning control source 800 across the holographic element 802followed by recording a new grating, which is suitable for the newwavelength. This process is repeated until many gratings are recordedand multiplexed in the holographic element. The approach of FIG. 7(B) issimilar except that the grating is recorded in element 810 vialithographic projector 812, utilizing a source of light 816 and aprojection mask 814. Also ionic implementation techniques accompaniedwith tuning can be used for replacing lithographic approaches. Forincreasing the tunability of the holographic filter, it is recommendedto record gratings by a combination of wavelength and electricalmultiplexing. A paper of Michal Balberg, Meir Razvag, Ele Refaeli andAharon Agranat, “Electric-field multiplexing of volume holograms inparaelectric crystals”, Appl. Opt. 37, 843-847(1998) teaches electricalfield multiplexing of images for the purpose of data storage. Incontrast our technique produces gratings. In this combined multiplexing(utilizing tunable laser such as a dye), many gratings are recorded,each corresponding with a different wavelength as well as a differentelectrical field. The tunability is achieved usually in any holographicmaterials with a large electro-optic coefficient. Tunability over alarge dynamic range is realized in holographic materials with quadraticelectro-optic effect such as KnBO₃.

[0079] Thus, our approach combines wavelength and electricalmultiplexing using interference patterns to write the gratings. Myapproach combines k-wake vector multriplexing with any tuning sourcewith any method of writing the grating. This is in contrast toBalberg-Arganat which was directed to holographic storage of images involume material

[0080] Through the reading process, if beam of light which consist ofseveral wavelength is incident on the this Bragg grating, and tuningsource voltages of increasing value are applied across the grating, thenthe Bragg grating should scan the various wavelengths. If a particularwavelength is to be selected by the demultiplexer, an appropriate DCvoltage, or other appropriate tuning source, is applied to the grating.However, multiplexing many gratings in this manner can be complicatedand require many steps of grating recording and is not very practicalfrom a fabrication point of view. Therefore I prefer to produce only onegrating which is the resultant grating of the entire multiplexed seriesof gratings. Assuming the central wave vector of the multiplexed gratingis given by Ko, and the number of the gratings which need to bemultiplexed is 2 m, with separation of ΔK between any two neighboringmultiplexed gratings, then the resultant multiplexed grating is given by

G(x)=e ^(ik) ^(_(o)) ^(x) sin c(Δkmx)  (1)

[0081] For the linear electro-optic tuning source it is possible towrite that $\begin{matrix}{{\Delta \quad k} = {\frac{2\pi \quad n}{\lambda_{o}}\left\lbrack {\frac{{\Delta\lambda}_{\quad}}{\lambda_{o}} + {2\pi \quad n^{3}r\quad \Delta \quad E}} \right\rbrack}} & (2)\end{matrix}$

[0082] where n is the material index of refraction, λ_(o) is thecenteral wavelength, and Δλ is the wavelength difference betweenneighboring channels, r is the effective electro-optic effect ΔE is theincrement in electric field in order to make the grating step onechannel in demultiplixing.

[0083] The above equation allow one to set up the grating specification,such as the central wavelength, number of channels, and the electricaltuning levels.

[0084] In the case of the lithographic fabrication of the mask, see FIG.7b, it is sufficient to multiplex one mask which has transmissivityproportional to G (x). In the case of holographic fabrication, all thatis needed is to attenuate the grating exp(iKoX) recording by white lightsource 816, which is proportional to sinc (ΔKmX) made by a mask 814 or804 in FIG. 7A using incoherent to coherent conversion processingtechniques. The variation in the sign of sinc(ΔKX) from positive tonegative can be overcome by encoding it as a transmissivity mask byvalues of 0 and 1 (instead of −1,1) and this should gave an approximatedsolution sinc(ΔK mX). This is not the only form of mask, other masks areappropriate depending on the tunability with other tuning sources, as isknown in the art, e.g..we may wish to multiplex several chirpedgratings.

[0085] A fringe pattern according to equation (1) can be produced viainterference between two wide slits, therefore storing the projection ofthe interference of the diffraction pattern from two slit with a planewave should be a straightforward method for production tunable gratingover many wavelength. This approach may be extended also for WDM base ontunable acoustic-optic tunable filter, where one can make the tunableacoustical grating to be generated via interference between two squareacoustical pulses(see for example (Optical network A practicalrespective, Rajiv Ramaswami and Kumar N. Sivarajan p 115 Morgan KaufmannPublishers Inc.) Though for doing this it better to use to acousticaltransducers.

[0086] Also one might think about an encoding approach for an easytechnique of fabrication a grating, which is tunable over manywavelengths. One encoding approach, which I suggest, relies on encodingthe above grating, by a grating, which has a variable K vector. Anotherapproach, which I suggest, is encoding the grating in binary form orother alternative form. For example, in the grating spacing coding formsone can select grating vector K(x)=Ko+K₁(x) so that at least for thefirst order approximation should gave

e ^(i(k) ^(₀) ^(+k) ^(₁) ^((x))x) ≈G(x)=|G(x)|e ^(r(x)) =e ^(ik) ^(₀)^(x) sin c(Δkmx) grating.  (3)

[0087] Making the real part of the above equation (3) equal, then it ispossible to show that $\begin{matrix}{{k_{1}(x)} = \frac{{arc}\left\lbrack {\sin \quad {c\left( {\Delta \quad {kmx}} \right)}} \right\rbrack}{x}} & (4)\end{matrix}$

[0088] In the binary coding form, one might select that $\begin{matrix}{{\gamma (x)} = \left\{ \begin{matrix}{{\phi_{1}\quad {for}\quad {\gamma (x)}} \geq \quad \pi} \\{{\phi_{2\quad}{for}\quad {\gamma (x)}} \leq \quad \pi}\end{matrix} \right.} & (5)\end{matrix}$

[0089] where φ1, φ2 are two phase steps or two absorption steps or acombination thereof. Adding the amplitude mask should be optional.

[0090] These coding approaches should not only make it easy tofabrication grating with lithographic approaches, but should also openthe possibility of fabrication of gratings using a stack of multi layersElectro-optic materials using a standard microelectronics and thin filmsdeposition fabrications procedures, or ion implementation approaches.The latter has significance in fabrication wide range tunabledistributed feed back lasers. It is possible to employ similarapproaches to the above, based on superposition of chirped gratings. Achirped grating has narrower band pass filter than a grating with aconstant k vector, thereby to increase the number of available channels.This tunable grating can be employed as a part of an add/dropwavelength-time multiplexer, in order to produce a tunable add/dropelement. (Optical network A practical respective, Rajiv Ramaswami andKumar N. Sivarajan p 100 Morgan Kaufmann Publishers Inc)

[0091] We have discussed the possibility of fabricating a Bragg gratingwhich is tunable in wavelength, but it is possible to make an angulargrating combined with tune multiplexing, which should have anapplication in designing a router for telecommunication purposes. It iswill known in holography, according to one of the most fundamentaltheories (see H. Kogelnick, Bell Syst. Tec. J. 48, 2909 (1969), thatgrating transmissivity or reflectivity is sensitive for both thewavelength and the angle of the incident light. This important featurecan be used to advantage by the present invention in the following areas(a) deflection phase sensitive detection (b) wavefront phase decryption(c) Speed decryption (d) Spatial noise filtering.

[0092] Regarding deflection sensitive detection, suppose that there isoptical pick-up made from a thick holographic element, and this opticalpick up is collecting light from a certain medium, e.g. CD, DVD,Magneto-optic disk, or a certain form of a microscopic medium. Thislight can be deflected from its original direction, due to any of thefollowing reasons: (a) going to new track, (b) deviation from thefocusing condition, (c) reading a new cell. Then the light which isreflected or transmitted out the optical pick-up is a function of thedeviation. Therefore, the measure of this deviation from the standarddirection is one way to decode the information on the medium. For CDapplications see: Masud Mansuripur, Chapter 31, Optical society ofAmerica, Handbook of optics I); see In microscopy, ”Implementtion of thescanning tomographic acoustic microscope for Multple-Angle tomographyRichard Y. Chiao and Hua Lee, PP 499-509, Acoustical Imaging Edited byHelmunt Ermert and Hans-peter Harjes Acoustical Imaging Vol 19).

[0093] In optical microscopy, tomography, CD, and DVD applications, thelight that is deflected from the medium is decoded by a partial blockingof the beam and demodulating the light via lock in detection.

[0094] However from a holographic point of view, there is no differencebetween deviation in Bragg condition in terms of wavelength or angle.Both deviation are analogous from holographic point of view; see thefollowing reference re the mismatch from Bragg conditions either bydeviation in the wavelength or the angle: H. Kogelnick, Bell Syst. Tec.J. 48, 2909 (1969).

[0095] This means instead of designing homodyne/heterodyne detectorsbased on mixing between frequency modulation and the tuning source, itis possible to design homodyne heterodyne detector which function bymixing angular deviation with tuning source. This feature should beextremely significant for most forms of optical microcopy-tomography, CDand DVD.

[0096] Regarding noise filtering, suppose the optical pick up iscollecting light being diffused within a portion of the body of apatient under medical examination, or from light scattered by a cell ina multi layered optical storage device. Through propagation of the lightfrom the required cell to the holographic element, the light is going tosuffer from scattering. This scattering produces optical noise. Thenoise generally doesn't satisfy the Bragg conditions, therefore itintensity is going to be degraded significantly after reflection ortransmission through the holographic element. Also, light scattered fromoscillating or other moving objects is usually associated with Dopplershift; essentially a change in the wavelength. In holographic pick-upsystems, this is going to change the Bragg conditions and hence theintensity of the transmitted or reflected light.

[0097] Regarding measuring wavefronts of light, in transmitting imageswithin the atmosphere, it is essential to measure wavefront aberrations.The common way to measure aberration is to use Hartmann sensor. Theprior art Hartman sensor of FIG. 8(a) consists of an array of microlenses 900, pinhole array 902 and CCD camera 904. The wavefront isfocussed via the lens array at different locations depend on thedeviation of the wavefront. The variation in focal points is a functionof the shape of the wavefront and it can be measured via the pinholearray 902, using the CCD camera to measure the intensity of thetransmitted light.

[0098] My Bragg grating can be used as an alternative replacement of theexpensive Hartman sensor. Assume that a Bragg grating was fabricated asresult of interference between two plane waves or deposition via a stackof thin films layers. Then if Bragg grating 906 in FIG. 8b was used toreceive a wave 907 coming from atmosphere, the wavefront of the beam isgoing to be decoded, depended on the slope of the beam wavefront, by theprovision of CCD 908. The variation in the beam wavefront is anindication of its slope, and has a direct relationship with K-wavevector variation. The variation of the wavevector is going to changeaccording to the tranmissivity or reflectivity of the Bragg grating, andhence the wave vector is going to be detected, measured or decoded. Thusin accordance with the present invention, a wave front of light of anincoming light beam is measured by providing a K-vector tunable Braggcell grating 906, directing the incoming light beam at the Bragg cellgrating; and measuring an intensity pattern of light emanating from saidK-vector Bragg cell, by for example a CCD detector 908, for indicatingvariations in slope of the wave front tuned at a selected wavelength.

[0099] This use of the Bragg grating has other advantages over the priorart Hartman sensor. If the Bragg grating is tunable over broad band ofwavelength, then this should allow diversity in measurement ofwavefront. This diversity is important to determine accurately theabsorption and the aberration results from the atmosphere. Such adiversity is impossible to perform with conventional Harman sensor.

[0100] The tunable Bragg grating can also be used to decode the shape ofthe wavefront of plane waves scattered from moving objects in both phaseand amplitude. This feature can be used in Lidar application to measurethe wind speed in aircraft flights. Using my broadband tunable cell,advantageously allows a diversity in measurements over many wavelengthsin contrast with prior approaches.

[0101] Another application, which may be considered, is to perform twodimensional homodyne heterodyne detection associated with deflectionsensitivity, on an oscillating object in a future non-scanning mode,with a broad beam to determine its topography. The two dimensional Bragggrating can perform simultaneous homodye detection on both Doppler shiftand the instantaneous aberration on beam wavefornt.

[0102] Regarding the time-wavelength division demultiplexer, wepreviously described how to combine wavelength division demultiplixingwith frequency division demultiplixing. However, frequency divisiondemultiplexing is used primarily in analog telecommunication systems,rather than in digital telecommunication systems. We now illustrate howour previous scheme can be used to combine time division and wavelengthdivision demultiplixing. FIG. 9a shows schematically a single channeltime-wave length division demultiplexing process. A beam of light 111consist of superposition of n beams with different wavelengths, allbeams are incident on tuneable cell 112, which is tuned by the tuningvoltage source 114. Let also assume that that each beam of the n beamscarries m synchronised time slots. An example would be transmission ofinformation from n different buildings, and in each building there are mapartments. For each building a certain wavelength is allocated forsending the information and for each apartment within the building, acertain time slot is allocated. We would like to demultiplex thisinformation. Let us assume that the cell 112 has been designed to have nswitching on modes represented by the peaked triangles 114 of FIG. 9b,and also n switching off ranges 113 between the on modes as shown. Inthe jth switch on mode a reflection (or transmission) of the j th wavelength occurs, and to achieve this, tuning of the tuning source for Tjlevel is required. The switch off ranges correspond to the DC levels ofT where there is no transmission (or reflection) of any wavelength.However, it is more practical to select the switching off mode withinthe switch off ranges, so that these switch off modes 113 are nearby theswitch on modes 114 as indicated by the arrow heads 115 in FIG. 9(b) Fordemultiplexing incoming information at a certain wavelength j and withina certain time slot i, the simplest way, is to perform synchronisedtuning of the cell to level Tj in the time slot ti, so that simultaneoustime and wavelength division demultiplexing occurs. However thisapproach can have some drawbacks. For tunabillity over many wavelengths,the voltage source should quickly jump between numerous tuning levelswith the required speed. For example, if the tuning source iselectrical, it may be required that the tuning source have both highvoltage and high current, and such a requirement can be burdensome. Amore practical approach is to divide the tuning levels into twocomponents, a large DC component, and a small incremental AC component.The DC component should be adjusted to establish one of the tuning offlevels 115, which is nearby the tuning level of the required wavelength,and a small incremental synchronised component is added to switch on therequired wavelength. This incremental component will be produced withinthe desired time slot, and thus the cell is periodically turned onduring the desired time slot. The cell is periodically turned on duringother time slots and at various wavelengths depending upon the DC levelassociated with the desired incremental time slot pulse.

[0103] Hence, for this application, the fluctuating (AC) component, ortemporal detection signal, of the tuning control voltage does notfunction as a frequency mixer hetrodyne detector described in priorembodiments, but instead periodically turns the Bragg cell on and off atthe various selected wavelengths to produce simultaneous TDM and WDMdemultiplexing. Thus, the fluctuating temporal signal in this embodimentcomprises a series of time slotted pulses. Two different time slots willthus usually have two pulse trains phase shifted with respect to eachother.

[0104] In the case where the tuneable cell doesn't have enoughtunability or tuning strength with respect to the tuning source, thenthe weak tuning cell can be replaced be cascaded or parallel cellstructure as described in FIG. 3. In this case each tuning cell may bedesigned to have two switching modes, one which is opaque, the other onetransmitted (or reflected) at a certain wavelength. However, thesearchitectures are more complicated. To avoid large number of connectionsand to avoid the requirement having which require wide range oftunability, I would recommend a solution, which lies between onetuneable cell approach and many tuneable cells approach. In this case itpossible to design the tuneable cell to have more than two switchingmodes but not all modes.

[0105] We have discusses combining frequency wave demultiplexing andtime wavelength demultiplexing, However, it is possible to combine allof the above discussed forms of multiplexing and demultiplexingsimultaneously. To do so, two cascaded tuneable cells, one for timemodulation, driven by frequency modulator and the other one whichfunction as time-wavelength division demultiplexer and a time slotswitch which is driven by the pulse generator. The time divisiondemultiplixing can be described as a special operation mode of the timeintegrative correlator. This mode of operation can be considered as verylong time integrative correlation between the input and a binary pulseof certain slot. Additional applications of the present inventioninclude spread spectrum communication and frequency hoping, a knowntechnique which was used in Radar systems and wireless telecommunicationto prevent jaming (Local & Metropolitan Area network, William Stalling1977 by Prentice-Hall, Inc 1977 p 367-372). Frequency hoping is used inboth digital and analog system. My wider range tunable cell can be usedfor such a purpose. Slower MEMs or other tunable devices are notsuitable for this purpose. In frequency hopping system, either theanalog or the binary data is fed into modulator, such as frequencyshifting keying (FSK), the resulting signal is centered around a basefrequency. A pseudorandom signal generator. At each successive bit ofthe random signal, a new frequency is selected from the table. In thereception end, the spectrum of the signal is demodulated using the samepseuderandom signal, which is used during transmission. The proposedmodulators can be used for this purpose. The DC term, which is used forWDM, can also be used also for frequency hopping purposes in both thetransmission and the receiving end.

[0106] Regarding TCP/IP header recognition: TCP/IP is the most frequentprotocols used in network technology. TCP stands for transmissioncontrol protocol, and IP stands for Internet protocol. For IP addressrecognition, my AND logical gate is used for this purpose. For exampleif there a sequence of bits in the data gram, such as 00010010, thereceiving host or router must generate a similar bit sequence and useAND logic gate in order to recognize the IP address. The tunable devicecan be used also as an AND gate. For recognition an address with00010010 sequence of bits, the AC voltage should simply be modulatedsynchronously with the same bit sequences of the incoming message. Ifthe results match for all of them, then this should be the rightaddress, if they don't match, then the address is the wrong address.

[0107] Two main advantages this optical recognition has over electronicrecognition using my AND gate. are

[0108] (1) The bits of are not necessarily monochromatic, this meansmore IP addresses can be added

[0109] (2) It is possible to combine frequency hoping coding with the IPaddress, such a combination is impossible to achieve using conventionalapproaches.

[0110] (3) Can increase the number of addresses in LAN, MAN and WANnetworking.

[0111]FIG. 10 shows the configuration of combined AND gate and frequencyhopping for secured telecommunication. In the input section, thetransmitter 200 a consist of light source 201, K-wave frequency selector202 a, which is driven by the tuning source 203 via a stream of bits ofdifferent tuning levels indicated at 204 a. The level of these bits 204a is selected in a way to generate light pulses of equal intensity, butwith different wavelengths as indicated at 205. This stream of lightpulses 205 are transmitted within the fiber 206 a. At the receiving end,the receiver 207 consists of tuning source 208 a, K-wave selector 209and detector 210 a. The tuning source of the receiver, synchronouslydrives the K-wave selector 209 with similar bits shown at 211,coincident in time with the bits generated by the transmitter tuningsource 203 in order to be able to accept the whole message. Thus, thetuning level control pulses at 204 a generated at the transmitter bytuning source 203 will be synchronized with, and produced at the sametime with, the tuning level control pulses 211, generated at thereceiver. The manner in which this synchronization is performed is knownto those familiar with the frequency hopping technique. One approachinvolves simultaneously reading the same pseudo-random number table atthe transmitter and the receiver to generate the synchronized controlpulses. If the tuning level control pulses have equal amplitudes, theAND gate function would be retained without the advantageous use offrequency hopping.

[0112] Regarding Space Division Routing Demultiplexing, the presentinvention can be employed to demultiplex light beams within a fiberoptic space division demultiplexer or router mixer. For a constantincoming beam wavelength, the aforesaid DC component applied to thetuned Bragg cell can be changed to select the angle of incidence of anaccepted beam of a number of beams directed at the Bragg cell at variousinput angles. In a similar way, there is also the possibility ofachieving angular tune multiplexing in holograms. Time divisionmultiplexing and routing can be combined on the same tunable cell inaccordance with my invention.

[0113]FIG. 11 shows a configuration of the router-mixer. The input 1101is a beam which consist of superposition of several monochromatic beams,each of the monochromatic beams carrying a temporal signal. This beam isincident on grating 1102 which is an encoded form of the aforesaid tunespatially multiplexed grating. The grating is tuned via tuning source1103 which consists of two components, the DC component, and thefluctuating component. The DC component To is the tuning component,which is responsible for routing a selected monochromatic component toits associated output port 1104. T (t) is the fluctuaing component whichis responsible for producing the aforesaid heterodyne functionalities,including time division demultiplixing as well the AND logic gatefunction.

[0114] The configuration can be extended also to include spread spectrumtechniques as well as combination of AND gate with spread spectrum. Forthe linear Electro-optic effect it possible to prove that for equally kspaced gratings on one plane, the multiplexed grating have very similarform to the one have been developed in equation 1 This can make thegrating to serve as both spatial and wavelength demultiplixer. Also itis possible to cascade two tunable cells one for wavelengthdemultiplixing and the other for the spatial demultiplixin.

[0115] Since variations of the above embodiments of the invention willbecome apparent to skilled workers in the art, the scope of theinvention is to be limited only by the terms of the following claims andart recognized equivalents thereto. For example, in the above designs,it was assumed that T₀ and T (t) must be produced by the same tuningsource, but in general To and T (t) have totally different tuningorigins. For example, To can be rotational tuning and T (t) can beelectrical. The devices, which I described so far, can be designed inbulk structure, or can be as a part of integrated opto-electronicdevices. Further these wide range tuning grating devices can beintegrated within a laser to provide distributed laser over manywavelengths.

[0116] Etalon, MEMS, or Mach-Zender interferometers, micro-fabricatedinterferometers, fibre based interferometers are dependent on theoptical path length as well the input wavelength, and this fact meansthat interferometers can be used in wavelength division demultiplexing.Likewise, gratings in volume material can also be employed which arealso sensitive to the variation in the incident beam direction as wellas wavelength. Either change in the input wavelength or in the beamdirection can be considered as a variation in the K-vector of thewavelength and beam orientation input signals. Thus the claimed “K-waveselector,” or “K-vector division demultiplexer” can demultiplex ordetect various input signals of different wavelengths and/or angles ofincidence. The term “detection” is not just hetrodyning but can includeapplication of time slotted pulses as in FIG. 9. The term “K-vectorselector” is intended to include arrays of discreet elements for certainapplications such as multi-head microscopy, and non-discreet elementsfor other applications such as the wavefront detection apparatus of FIG.8b. The term “transmitted”, in connection with K-vector selectortransmission of light is intended to include the equivalent reflectionmode. Whenever heterodyne detection is applied, it also be replaced bytime integrative correlation. “Hetrodyne detection” can have a broadmeaning, and could include at least some, if not all of thesefunctionality's: phase sensitive detection, lock in detection, base banddemodulation, frequency division demultiplexing, frequency conversion.Spectroscopic correlation is a wide range time integrative correlation.Hetrodyne detection is intended to include homodyne detection. The term“modulation” can take various forms including, time, space-time, phase,frequency and K vector modulation. The spectroscopic correlation, whichwas described in my U.S. utility patent application Ser. No. 09/332,404,filed Jun. 14, 1999, entitled “Spectroscopic Time IntegrativeCorrelation for Rapid Medical Diagnostic and Universal Image Analysis”may be considered as a form of time integrative correlation with asevere Doppler shift. The Doppler shift is large, up to the extent ofchanging the colors. Time division demultiplixing (TDM) is a form ofbroad band time integrative correlation with asynchronous binary slotpulses, which represent the time slots. The AND gate can be consideredas a broad band asynchronous bits correlation between the input andtemplate bits. The “optical image under examination’ is intended toinclude virtually any type of image including a microscopic, tomographicor remote target image.

[0117] In the special case of very fast modulation, the k-vectorselector can act as a low pass filter so that the CCD detector can beeliminated. Thus the k-vector low pass filter can act as the claimed“time integrating detector means.” The “tuning means” are is not limitedto be electrical; it can be replaced by other tuning sources dependingon the materials used for fabrication of the devices. Some of the tuningmeans can include electrical, optical, acoustical, piezoelectric,elasto-optic, magneto-optics, magnetic, stress, mechanical, cellelectro-optic effect. The term “fluctuating temporal signal” and “DCtuning signal” are not to be restricted to electrical signals, but couldcomprise stress, thermal changes, or the like mentioned above.

I claim:
 1. High resolution pickup device for reading data off of andwriting upon an optical recording medium comprising: (a) a k-vectorselector tunable cell for processing k-vector modulated temporal lightsignals read off of said optical recording medium; and (b) focusingmeans for directing said k-vector modulated temporal light signalsprocessed by said k-vector selector on light beam detector means.
 2. Thepickup device of claim 1 including (c) tuning control means for applyinga fluctuating temporal tuning signal to said k-vector selector tunablecell that is phase locked with respect to a fundamental repetitionfrequency of said temporal light signals read off of said opticalrecording medium, for enhancing the tracking accuracy of said highresolution pickup.
 3. The pickup device of claim 1 wherein said focusingmeans includes an electrically controllable means for changing the focallength of said focusing means in response to the application of varyingtuning control signals applied thereto.
 4. The pickup device of claim 2including focusing means having an electrically controllable means,positioned within said k-vector selector tunable cell, for changing thefocal length of said focusing means in response to the application ofvarying tuning control signals applied thereto.
 5. The pickup device ofclaim 1 wherein said focusing means comprises a high resolutionholographic lens.
 6. The pickup device of claim 2 wherein said focusingmeans comprises a high resolution holographic lens.
 7. The pickup deviceof claim 3 wherein said focusing means comprises a high resolutionholographic lens.
 8. The pickup device of claim 4 wherein said focusingmeans comprises a high resolution holographic lens.
 9. The pickup deviceof claim 5 wherein said high resolution holographic lens comprises aninterference pattern between light emitted from a tiny point source oflight and a broad light beam.
 10. The pickup device of claim 9 whereinsaid tiny point source of light has a diameter of about one micron orless.
 11. The pickup device of claim 5 wherein said high resolutionholographic lens comprises an interference pattern between light emittedfrom a tip of an optical fiber and a broad light beam.
 12. The pickupdevice of claim 1 wherein said tuning control means applies a pluralityof DC wavelength establishing electrical control signals to saidK-vector selectable tunable cell for selectively altering the focallength of said electrically controllable lens means for in turn enablingreading data off of a plurality of variously positioned opticalrecording elements.
 13. The pickup device of claim 2 wherein said tuningcontrol means applies a plurality of DC wavelength establishingelectrical control signals to said K-vector selectable tunable cell forselectively altering the focal length of said electrically controllablelens means for in turn enabling reading data off of a plurality ofvariously positioned optical recording elements.
 14. The pickup deviceof claim 4 wherein said tuning control means applies a plurality of DCwavelength establishing electrical control signals to said K-vectorselectable tunable cell for selectively altering the focal length ofsaid electrically controllable lens means for in turn enabling readingdata off of a plurality of variously positioned optical recordingelements.
 15. Apparatus for detecting temporally modulated opticalsignals comprising: (a) a time integrating optical signal detectormeans; (b) a K-vector selector for detecting K-vector modulated temporallight signals applied thereto and also having focusing means associatedtherewith for focusing light beams upon said time integrating opticaldetector; (c) optical signal input means for directing said temporallymodulated optical signals at said K-vector selector; and (c) tuningcontrol means for applying (c-1) an hetrodyne phase locked matchingtemplate signal to said K-vector selector for causing said K-vectorselector to hetrodyne detect said temporally modulated optical signals;(c-2) A DC signal to said K-vector selector for altering the K-vectordiscrimination of said K-vector selector and thus focal lengths of saidholographic lens focusing means.
 16. Apparatus of claim 15 wherein saidK-vector selector comprises an electrically tunable K-wave vector cell.17. Apparatus of claim 15 wherein said optical signal input meanscomprises an optical data storage medium.
 18. Method of producing aholographic lens comprising the steps of: (a) interfering lightemanating from a tiny point source of light with a plane wave front oflight; and (b) recording the interference pattern resulting from step(a) on a holographic element.
 19. The method of claim 18 wherein saidtiny point source of light is an optical fiber tip.
 20. The method ofclaim 18 wherein said tiny point source of light has a diameter of lessthan one micron.